When, as in subsea well riser applications, it is necessary to provide buoyancy members capable of withstanding large hydrostatic forces and having good resistance to impact, it has been the usual practice to make the buoyancy member in the form of a hollow metal structure or a body of syntactic foam. Buoyancy members so produced have been expensive, excessively heavy in the case of metal structures, and difficult from the standpoint of quality control in the case of syntactic foam bodies. There has accordingly been a continuing need for methods by which buoyancy members could be produced without requiring metal structures or use of syntactic foam.